The need for access holes in the walls, covers and chassis of enclosed electronic equipment is well known. These holes allow access for adjusting and/or testing internal components of an assembly while enclosed in radio frequency shielding. Once the adjusting and/or testing is completed, the access holes must be covered or plugged. That is because discontinuities, such as access holes, act as antennae for the electromagnetic fields from the electrical circuitry adjusted or tested by means of such holes, According to well known electromagnetic field theory, the amount and frequency of the electromagnetic energy that is spuriosly emitted depends upon the frequency and power level of the enclosed electrical circuitry. The enclosed circuitry may be for digital logic, computers, radios or telephone equipment. All of these use radio frequency signals that can become spurious emissions if not appropriately contained.
The known cover 100 for access holes , as seen in FIG. 1, has a domed or button shaped body 102 and has curved, springy appendages 104 coming out from the bottom circumference of the body. These appendages 104 are crafted such that when the right sized cover 100 is placed over a hole (not shown) and pressed in, the appendages 104 are initially forced inward by the sides of the hole and then as the bottom of the button nears the surface in which the hole is located their springiness and their shapes allow the appendages to expand outward. Also, because of the shape of the appendages 104, this expanding action against the edges of the hole actually draws the cover 100 down toward the surface and locks it in place. To be effective, the known cover 100 must be bigger than the hole it is in--otherwise the spring action would pull the body portion 102 into the hole. This size difference between the cover 100 and the hole it goes into prevents covering a hole inside of another a hole unless the holes and their respective covers are made progressively and substantially larger towards the outside of the enclosure. Covers within covers are also hard to install. Furthermore, the appendages must be shaped for a range of hole depths and material thicknesses. If the hole is too deep, the pulling action and the locking do not occur. If the hole is very shallow, the pulling action and the locking will not occur either and the cover 100 will be loose and less effective. Furthermore, the appendages 104 as they extend into the enclosure can and will begin to act as antennas for emissions within the enclosure if the effective size of the appendages 104 is approximately a quarter wavelength. This often leads to unintended coupling of circuits when a cover 100 is installed.
Thus, it is an object of the present invention to provide a cover or plug that mounts flush with the top and bottom surfaces of the hole it is inserted into.
It is another object of the invention to provide a cover or plug that can be readily passed through a first hole to cover an interior access/test hole.
It is a further object of the present invention to provide a locking on almost any thickness of material.